Multifunctional optical filter for stereoscopic display device and stereoscopic display device comprising the same

ABSTRACT

Provided are a multifunctional optical filter for a stereoscopic display device and a stereoscopic display device including the same. The multifunctional optical filter includes a 3D filter layer patterned into a first region adjusting a polarization state of a right-eye image and a second region adjusting a polarization state of a left-eye image, and a color filter layer having a RGB pattern, wherein the RGB pattern of the color filter layer and the pattern of the 3D filter layer are formed to correspond to each other.

TECHNICAL FIELD

The present invention relates to an optical filter for a stereoscopicdisplay device and a stereoscopic display device including the same, andmore particularly, to a multifunctional optical filter for astereoscopic display device for performing a color filtering functionand a three-dimensional filtering function through only a single filterand a stereoscopic display device including the same.

BACKGROUND ART

A stereoscopic display device is a new concept for an image displaydevice for improving a quality level of visual information by providinga three-dimensional image similar to an actual image, which, to anobserver, looks and feels quite different to a related arttwo-dimensional image. In general, the reason for which peopleexperience a three-dimensional visual effect is well known, in that whenpeople view an object, there is a time difference between imagesstriking the right and left eyes. That is, since people's eyes arespaced apart from each other by about 65 mm, images from slightlydifferent directions reach them, so that a three-dimensional effect isrealized due to binocular disparity caused when stereoscopic images aredisplayed. As a result of this, stereoscopic images may be realizedthrough a method of displaying images having a time difference to bothof an observer's eyes.

A related art stereoscopic display device is largely classified into adisplay device with a pair of polarized glasses and a display devicewithout polarized glasses. A stereoscopic display device using a pair ofpolarized glasses projects left- and right-eye images having differentrespective polarization properties which allow only a left-eye image tobe projected onto a left-eye lens and only a right-eye image to beprojected onto a right-eye lens through polarizing plates attached tothe pair of polarized glasses, thereby providing a stereoscopic visualeffect. This technique of using a pair of glasses requires a user towear inconvenient polarized glasses, but has less viewing anglelimitations and demands relatively simple manufacturing processes.

In general, a related art stereoscopic display device using a pair ofpolarized glasses includes an image generating unit, which includes aleft-eye image unit for generating a left-eye image and a right-eyeimage unit for generating a right-eye image, and a filter unit, whichalters polarization states of left-eye image light and right-eye imagelight generated from the image displaying unit.

At this point, the image generating unit may include a display panelsuch as a Liquid Crystal Display (LCD) and a Plasma Display Panel (PDP).For example, the image displaying unit includes a Thin Film Transistor(TFT)-array substrate, which includes a transistor and a pixelelectrode, a color filter substrate, which includes a transparentelectrode and a color filter layer, and liquid crystal cells, which arearranged two-dimensionally in a parallel direction or a verticaldirection.

Furthermore, the filter unit includes a polarizing film, or a polarizingplate having a phase difference plate attached, all of which arepatterned in correspondence to the left-eye image display unit and theright-eye image display unit, respectively. The filter unit is typicallyattached to an external color filter substrate.

However, in the case of the related art stereoscopic display device,since there is a thick glass substrate between an optical filter and acolor filter layer of an image display unit, right-eye image light andleft-eye image light from the image display unit are projected intorespective opposite eyes, thereby causing crosstalk. As a result ofthis, it becomes difficult to obtain a clear three-dimensional image.

In addition, it is important to accurately position the pixels of animage display unit and the pattern of an optical filter in astereoscopic image display device. However, when the pixels of the imagedisplay unit do not correspond to the pattern of the optical filter,right-eye image light and left-eye image light are not properlyseparated so that three-dimensional images may not be accuratelyobtained. Furthermore, in relation to the related art stereoscopicdisplay device, it is difficult to precisely match the pixels of animage display unit and the pattern of an optical filter.

DISCLOSURE Technical Problem

An aspect of the present invention provides an optical filter for astereoscopic display device for reducing crosstalk and preventingquality deterioration due to the mismatch of pixels and a pattern of theoptical filter and a stereoscopic display device including the same.

Technical Solution

According to an aspect of the present invention, there is provided amultifunctional optical filter for a stereoscopic display deviceincluding: a 3D filter layer patterned into a first region adjusting apolarization state of a right-eye image and a second region adjusting apolarization state of a left-eye image; and a color filter layer havinga RGB pattern, wherein the RGB pattern of the color filter layer and thepattern of the 3D filter layer are formed to correspond to each other.

The multifunctional optical filter for a stereoscopic display device maybe attached to an outer side of a display panel in a stereoscopicdisplay device.

The multifunctional optical filter for a stereoscopic display device mayfurther include an adhesive layer between the 3D filter layer and thecolor filter layer.

The multifunctional optical filter for a stereoscopic display device mayfurther include an adhesive layer on the uppermost layer of the opticalfilter.

The color filter layer may be formed through a printing method or aphotolithography method.

The color filter layer may be formed through an inkjet printing methodor a gravure printing method.

According to another aspect of the present invention, there is provideda stereoscopic display device comprising the multifunctional opticalfilter for a stereoscopic display device.

According to another aspect of the present invention, there is provideda stereoscopic display device including: an image generating unitcomprising an upper substrate having a transparent electrode on one sidethereof, a lower substrate spaced apart from the upper substrate andhaving a transparent electrode on one side thereof, and a liquid crystalcell interposed between the upper substrate and the lower substrate; andan optical filter comprising a 3D filter layer patterned into a firstregion adjusting a polarization state of a right-eye image and a secondregion adjusting a polarization state of a left-eye image and a colorfilter layer having a RGB pattern, the optical filter being disposed atan outer side of the upper substrate.

Advantageous Effects

An optical filter of the present invention performs a color filteringfunction and a three-dimensional filtering function through only onefilter. Therefore, no color filter is required on a substrate in animage generating unit when the optical filter of the present inventionis used.

Moreover, in a case of the optical filter of the present invention,since a color filter and a three-dimensional filter are integrated intoa single body, crosstalk may be effectively reduced due to a shortdistance between pixels and a three-dimensional filter.

Furthermore, according to the present invention, since the RGB patternof a color filter is directly formed on the pattern of athree-dimensional filter, the RGB pattern and the pattern of thethree-dimensional filter are accurately formed to correspond to eachother. Consequently, a high quality three-dimensional image can beachieved.

In addition, the optical filter of the present invention is disposed onan outer side of a substrate in an image generating unit (that is, adisplay panel).

DESCRIPTION OF DRAWINGS

The above and other aspects, features and other advantages of thepresent invention will be more clearly understood from the followingdetailed description taken in conjunction with the accompanyingdrawings, in which:

FIGS. 1 to 5 are views illustrating multifunctional optical filters fora stereoscopic display device according to embodiments of the presentinvention;

FIG. 6 is a view of a stereoscopic display device according to anembodiment of the present invention; and

FIG. 7 is a graph illustrating measured crosstalk rates.

BEST MODE

Exemplary embodiments of the present invention will now be described indetail with reference to the accompanying drawings.

FIGS. 1 to 5 are views illustrating multifunctional optical filters fora stereoscopic display device according to embodiments of the presentinvention.

As shown in FIGS. 1 to 5, the optical filter of the present inventionincludes a 3D filter layer 100 and a color filter layer 200.

The 3D filter layer 100 is used to realize a stereoscopic image bychanging polarization states of right-eye image light and left-eye imagelight. The 3D filter layer 100 includes a first region 110 for adjustinga polarization state of the right-eye image light and a second region120 for adjusting a polarization state of the left-eye image light. Forexample, the 3D filter layer 100 includes a retardation film, which ispatterned to allow the first region and the second region to havedifferent respective phase difference values. At this point, the patternof the 3D filter layer 100 may be striped or a grid shaped, but is notlimited thereto.

For example, the 3D filter layer 100 includes forming a patterned liquidcrystal alignment layer on a base film, coating a liquid crystalthereon, hardening it with ultraviolet rays to fix an alignment of theliquid crystal, and adjusting a polarization state. At this point,patterning the alignment layer may be performed through various methods.For example, one method includes alternately forming differentrespective liquid alignment layers in certain portions corresponding tothe first region and the second region. Another method includes formingan alignment layer on an entire surface of a base film and forminganother alignment layer overlapping on a portion corresponding to thesecond region on the alignment layer. Another method includes forming analignment layer on an entire surface of a base film and projectingpolarized light in different respective directions to the first regionand the second region by using a photomask. A liquid crystal is alignedon the patterned alignment layer formed through the above methods, so asto realize the first region and the second region having differentrespective alignment directions.

Next, the color filter layer 200 serves to realize a color image andincludes a RGB pattern. At this point, the RGB pattern of the colorfilter layer 200 is formed to correspond to the pattern of the 3D filterlayer 100.

For example, the color filter layer 200 may be manufactured through aphotolithography method using a color photosensitive material or aprinting method. If the printing method is used, it may include aninkjet printing method or a gravure printing method.

Meanwhile, according to the present invention, the 3D filter layer 100and the color filter layer 200 may be stacked on a base film 300. Atthis point, their stacking order may vary. That is, as shown in FIG. 1,the color filter layer 200 may be formed first on the base film 300 andthen the 3D filter layer 100 may be formed thereon. As shown in FIG. 2,the 3D filter layer 100 and the color filter layer 200 may besequentially formed on the base film 300.

Moreover, as shown in FIG. 5, the optical filter of the presentinvention may be manufactured through a method including forming the 3Dfilter layer 100 on the base film 300, forming the color filter layer200 on another base film 500, and bonding the two base films 300 and 500with an adhesive layer 400, besides a method of sequentially stackingthe 3D filter layer 100 and the color filter layer 200 on one base film.

The base films 300 and 500 may be made of a film having excellent lighttransmittance but are not especially limited thereto. For example, thebase films 300 and 500 may include a trichloroacetate film, apolyethylene terephthalate film, a cycloolefin copolymer film, apolyethylene naphthalate film, a celluose acetate film, a cellulosebutyrate film, a cellulose propionate film, an ethyl cellulose film, anacrylic film, a polyvinyl alcohol film, and a polyethylene film.

Meanwhile, the optical filter may further include an adhesive layer 400in addition to the 3D filter layer 100 and the color filter layer 200.The adhesive layer 400 may be disposed on the uppermost layer of theoptical filter as shown in FIG. 3 and may be disposed between the 3Dfilter layer 100 and the color filter layer 200 as shown in FIG. 4.

When the adhesive layer 400 is formed on the uppermost layer of theoptical filter, it is used to attach the optical filter to a displaydevice. The adhesive layer 400 may include an acrylic adhesive, a rubberadhesive, and a silicon adhesive but an acrylic adhesive havingexcellent light transmittance may preferably be used for the adhesivelayer 400. Additionally, in this case, a release film 700 may beadditionally attached to the adhesive layer 400 in order to preventforeign substance attachment. The release film 700 is removed when theoptical filter is attached to the display device. Then, the opticalfilter is attached to the display device. When the adhesive layer 400 isformed, since the optical filter is detachable from the surface of thedisplay device, the color filter layer 200 or the 3D filter layer 100may be easily replaceable in the event it is damaged or malfunctions.

Moreover, after the adhesive layer 400 is formed, if the color filterlayer 200 is formed through an inkjet printing method, a color filterpattern is printed on the adhesive layer 400. The adhesive layer 400serves as an ink reception layer, thereby improving ink dyeing power.

Meanwhile, a thickness of the adhesive layer 400 may be from about 5 μmto about 30 μm. If a thickness of the adhesive layer 400 is less thanabout 5 μm, accurate coating may be difficult and, if a thickness of theadhesive layer 400 is more than about 30 μm, an amount of an adhesiveused may be increased.

When the optical filter of the present invention is used, since thedistance between the RGB pixels of the color filter layer 200 and the 3Dfilter layer 100 is relatively short, crosstalk is greatly reduced.Additionally, in a case of the optical filter of the present invention,since the color filter layer 200 and the 3D filter layer 100 areintegrated into a single body, the RGB pattern and the 3D filter patternmay be formed to accurately correspond to each other and, as a result ofthis, a high quality 3D image may be realized.

Meanwhile, the optical filter of the present invention may be attachedto an outer side of a display panel in an image display device. Here,the display panel serves to generate a stereoscopic image. When theoptical filter is disposed on the outer side of the display panel forgenerating a stereoscopic image, a panel formed of a glass material ismanufactured and then a process for attaching the optical filter to theouter side of the display panel is performed. Thus, since a typical hightemperature process of more than about 200° C. used for an LCD panelmanufacturing process or a typical high temperature process of more thanabout 500° C. used for a PDP manufacturing process is not performed, afilm having a thermal resistance to more than about 200° C. is not usedbut a typical film is used. The typical film may include atrichloroacetate film, a polyethylene terephthalate film, a cycloolefincopolymer film, a polyethylene naphthalate film, a celluose acetatefilm, a cellulose butyrate film, a cellulose propionate film, an ethylcellulose film, an acrylic film, a polyvinyl alcohol film, and apolyethylene film. These films are superior to ahigh-temperature-resistant polyimide film in aspects of transparency,pigmentation, and cost. Additionally, a liquid crystal alignment layerused for a 3D filter layer or a pigmentation layer used for a colorfilter layer may be formed of a material having a low heat resistance.Moreover, since the optical filter of the present invention may bedetachable from the substrate of the stereoscopic display device, when adefect or damage occurs in the color filter layer or the 3D filterlayer, the optical filter may be easily repaired or replaceable, therebyfacilitating manufacturing processes.

In another aspect of the present invention, a stereoscopic displaydevice including the optical filter is provided. In more detail, thestereoscopic display device of the present invention includes an imagegenerating unit for generating an image light and an optical filter.

At this point, the optical filter is the same as above. The imagegenerating unit may generate left-eye image light and right-eye imagelight and may be a typical display panel such as an LCD panel or a PDPpanel. However, according to the present invention, since the opticalfilter includes a color filter, no color filter is required on thesubstrate of the display panel.

FIG. 6 is a view of a stereoscopic display device according to anembodiment of the present invention.

As shown in FIG. 6, the stereoscopic display device of the presentinvention includes an upper substrate 610, a lower substrate 620, animage generating unit 600 formed of a liquid crystal cell 650 interposedbetween the upper substrate 610 and the lower substrate 620, and anoptical filter 10 disposed at the outer side of the upper substrate 610in the image generating unit.

At this point, the upper substrate 610 and the lower substrate 620 maybe formed of a material having excellent light transparency and, forexample, may be include a glass or plastic substrate. Additionally,transparent electrodes 630 and 640 for applying power to the liquidcrystal cell 650 are formed on facing surfaces of the upper substrate610 and the lower substrate 620.

The liquid crystal cell 650 serves to represent an on/off state and agrey state of a pixel by adjusting the transmittance of a polarizedlight and may have the same structure as a typical LCD device.

Meanwhile, the optical filter 10 is disposed on the outer side of theupper substrate 610 and includes a 3D filter layer 100, which ispatterned into a first region 110 for adjusting a polarization state ofa right-eye image and a second region 120 for adjusting a polarizationstate of a left-eye image, and a color filter layer 200 having a RGBpattern. Since detailed descriptions of the optical filter 10 aredescribed above, overlapping descriptions will be omitted.

MODE FOR INVENTION

Hereinafter, the present invention will be described in more detailaccording to embodiments of the present invention.

Embodiment 1

After a first alignment layer was comprehensively applied to atrichloro-acetate film, +45° polarized UV light was projected onto theresult to harden the first alignment layer. Then, a second alignmentlayer was applied to the first alignment layer in a parallel line shapeand −45° polarized UV light was projected onto the result to harden thesecond alignment layer. Next, a liquid crystal was coated on the resultto harden it so that a 3D filter layer having a parallel line shape wasformed.

An acrylic adhesive was uniformly applied to the 3D filter layer with a20 μm thickness to form an adhesive layer.

A color ink was applied to the adhesive layer through an inkjet methodto be aligned orthogonal to the lines of the 3D filter layer and theresult was dried to form a color filter layer. As a result of this, anoptical filter was finally manufactured.

After a release film was removed from the optical film, the optical filmwas attached to an LCD device to manufacture a stereoscopic displaydevice.

Embodiment 2

In the same manner as embodiment 1, after a 3D filter layer in aparallel line shape was formed on a trichloro-acetate film, a color inkwas applied to be aligned orthogonal to the lines of the 3D filter layerthrough a gravure printing machine and was then dried to form a colorfilter layer.

An acrylic adhesive was uniformly applied to the color filter layer witha 20 μm thickness and then a release film was attached thereon tomanufacture an optical filter.

After the release film was removed from the optical filter, the opticalfilter was attached to an LCD device to manufacture a stereoscopicdisplay device.

Embodiment 3

Except that a photolithography method was used to form a color filter,embodiment 3 uses the same method as embodiment 2.

Embodiment 4

In the same manner as embodiment 1, a 3D filter layer in a parallel lineshape was formed on a trichloro-acetate film.

An acrylic adhesive was uniformly applied to a polyethyleneterephthalate film with a 20 μm thickness and a color ink is appliedthrough an inkjet method on the adhesive layer to be aligned orthogonalto the lines of the 3D filter layer and was then dried, in order to forma color filter layer.

After the trichloro-acetate film having the 3D filter layer and thepolyethylene terephthalate film having the color filter layer werelaminated, an adhesive was coated on the outer side of the polyethyleneterephthalate film and a release film was attached thereon tomanufacture an optical filter.

After the release film was removed from the optical filter, the opticalfilter was attached to an LCD device to manufacture a stereoscopicdisplay device.

Embodiment 5

Except that a color filter layer was formed on a cycloolefin copolymerfilm, a stereoscopic display device was manufactured through the samemethod as the embodiment 4.

COMPARATIVE EXAMPLE

A single 3D filter, which was not integrated with a color filter, wasmounted on the external surface of an available LCD panel having a colorfilter between an upper substrate and a transparent electrode, in orderto manufacture a stereoscopic display device.

Crosstalk rates were measured from the stereoscopic display devices ofembodiments 1 to 5 and the comparative example.

<Measurement Conditions>

Pixel pitch: about 0.54 mm

Glass thickness: about 0.63 mm

multifunctional filter thickness: about 0.2 mm

Observation distance: about 1500 mm

Crosstalk rate XT(θ) defined as the following Equation (1).

XT(θ)=(XT _(L)(θ)+XT _(R)(θ))/2   Equation (1):

Moreover, in Equation (1), XT_(L)(θ) and XT_(R)(θ) are defined as thefollowing Equations (2) and (3).

XT _(L)(θ)=(R _(L)(θ)−B _(L)(θ))/(L _(L)(θ)−B _(L)(θ))×100%   Equation(2):

XT _(R)(θ)=(L _(R)(θ)−B _(R)(θ))/(R _(R)(θ)−B _(R)(θ))×100%   Equation(3):

Where

B_(L) represents brightness when all pixels realizing right-eye imagelight and left-eye image light are in a black mode and the left-eyeimage light is observed at a viewing angle θ through a left-eye lensunit of polarized glasses,

L_(L) is brightness when a pixel realizing right-eye image light is in ablack mode, a pixel realizing left-eye image light is in a white mode,and the left-eye image light is observed at a viewing angle θ through aleft-eye lens unit of polarized glasses,

R_(L) is brightness when a pixel realizing right-eye image light is in awhite mode, a pixel realizing left-eye image light is in a black mode,and the left-eye image light is observed at a viewing angle θ through aleft-eye lens unit of polarized glasses,

B_(R) represent brightness when all pixels realizing right-eye imagelight and left-eye image light are in a black mode and the right-eyeimage light are observed at a viewing angle θ through a right-eye lensunit of polarized glasses,

L_(R) is brightness when a pixel realizing right-eye image light is in ablack mode, a pixel realizing left-eye image light is in a white mode,and the right-eye image light is observed at a viewing angle θ through aright-eye lens unit of polarized glasses, and

R_(R) is brightness when a pixel realizing right-eye image light is in awhite mode, a pixel realizing left-eye image light is in a black mode,and the right-eye image light is observed at a viewing angle θ through aright-eye lens unit of polarized glasses.

FIG. 7 is a graph illustrating measured crosstalk rates. The measuredvalues of the embodiments 1 to 5 show the same level within ameasurement error. Through FIG. 7, it is shown that the crosstalk ratesof the embodiments 1 to 5 are significantly lower than that of thecomparison example.

While the present invention has been shown and described in connectionwith the exemplary embodiments, it will be apparent to those skilled inthe art that modifications and variations can be made without departingfrom the spirit and scope of the invention as defined by the appendedclaims.

SEQUENCE LIST TEXT

-   100: 3D filter layer-   110: first region-   120: second region-   200: color filter layer-   300, 500: base film-   400: adhesive layer-   610: upper substrate-   620: lower substrate-   630, 640: transparent electrode-   650: liquid crystal cell-   700: release film

1. A multifunctional optical filter for a stereoscopic display devicecomprising: a 3D filter layer patterned into a first region foradjusting a polarization state of a right-eye image and a second regionfor adjusting a polarization state of a left-eye image; and a colorfilter layer having a RGB pattern, wherein the RGB pattern of the colorfilter layer and the pattern of the 3D filter layer are formed tocorrespond to each other.
 2. The multifunctional optical filter for astereoscopic display device of claim 1, wherein the optical filter isattached to an outer side of a display panel in a stereoscopic displaydevice.
 3. The multifunctional optical filter for a stereoscopic displaydevice of claim 1, further comprising an adhesive layer between the 3Dfilter layer and the color filter layer.
 4. The multifunctional opticalfilter for a stereoscopic display device of claim 1, further comprisingan adhesive layer on the color filter layer of the optical filter. 5.The multifunctional optical filter for a stereoscopic display device ofclaim 1, wherein the color filter layer is formed through a printingmethod.
 6. The multifunctional optical filter for a stereoscopic displaydevice of claim 5, wherein the color filter layer is formed through aninkjet printing method or a gravure printing method.
 7. Themultifunctional optical filter for a stereoscopic display device ofclaim 1, wherein the color filter layer is formed through aphotolithography method.
 8. A stereoscopic display device comprising themultifunctional optical filter for a stereoscopic display device ofclaim
 1. 9. (canceled)